The worst spring dust day of 2012 may be behind us -- it was Tuesday, and the air quality was still moderate, says city air quality expert Steve Morris.
Dust, visible as haze sometimes at its early morning peak, is about the same as usual for this time of year, Morris said.
The city's air quality typically worsens during early April when dirt reappears on the roads and temperature inversions prevent it from rising and dispersing, Morris said.
But as the air warms and streets are cleaned, the pollution level drops, he said. Warmer days cause more mixing action in the air and that reduces the concentration of dust.
The federal government rates air quality on a scale of 0 to 150, where 0 to 50 is good, 51 to 100 is moderate, and above that is "unhealthful for sensitive groups."
The city measures air pollution along Tudor Road near Dale Street.
Dust particulates caused the air quality index rating to shift from good to moderate on April 9 this year. Our pollution level stayed in the moderate range through Tuesday and then returned to good Wednesday.
The worst day this spring hit 79 on the federal scale.
In 2010, Anchorage's air pollution actually violated the federal standard of 100. Traffic-generated dust on Tudor Road one April day kicked the reading up to 106.
Both the state Department of Transportation and the city are well into street cleaning this year, Morris said.
Reach Rosemary Shinohara at rshinohara@adn.com or 257-4340.
